• Communications for Statistical Applications and Methods
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• 제13권3호
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• pp.651-656
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• 2006

Wu and Clements-Croome (2005) investigate the optimization problem of PM policies for situations where the quality of PM is a random variable with a certain probability distribution. However, they assume that the cost of preventive maintenance is constant, not depending on the quality of PM. Thus, this paper considers a periodic PM model when PM cost depends on the quality of PM activity. The optimal PM policy are presented for the extended PM model and the numerical examples are presented for illustrative purpose.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.198-205
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• 2009

일반적으로 철도차량은 획득비용보다 운영 유지보수비용이 높다는 것이 알려져 있다. 운영 유지보수비용의 절감을 위해서는 운영 유지보수 비용 측면에서 효율적으로 설계된 철도차량을 획득하는 것이 매우 중요하다. 따라서 철도차량의 획득단계에서부터 운영 유지보수비용을 포함한 수명주기비용을 고려하는 것이 필요하다. 본 연구는 철도차량의 획득단계에서 수명주기비용을 고려하기 위한 절차 및 수명주기비용 모형을 제시한다.

• 대한전기학회논문지
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• 제41권1호
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• pp.9-17
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• 1992

Proper resource allocation is also a very important topic in power system problems, especially in operation and planning. One such is optimal maintenance problem in operation and planning. Least cost and highest reliability should be the subjects to be pursued. A probabilistic operation simulation model developed recently by authors is applied to the proboem of optimal maintenance scheduling. Three different methods are compared, marginal maintenance cost, levelized risk and maintenance space. The method by the marginal maintenance costs shows the least cost, the highest reliability and the highest maintenance outage rates. This latter characteristics may considerably influence the results of genetation planning, because the usual maintenance outages obtained from the other methods have shown to be lower.

• 한국신뢰성학회지:신뢰성응용연구
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• 제15권1호
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• pp.6-11
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• 2015

Maintenance plays an important role in keeping product availability, reliability and quality at an appropriate level. In this paper, two-types of maintenance policies are studied following the expiration of two-dimensional (2D) free replacement warranty. Both the fixed-maintenance-period policy and the variable-maintenance-period policy are based on a specified region of the warranty defined in terms of age and usage where all failures are minimally repaired. An accelerating failure time (AFT) model is used to allow for the effect of usage rate on product degradation. The maintenance model that arises following the expiration of 2D warranty is discussed. The expected cost rates per unit time from the user's point of view are formulated and the optimal maintenance policies are determined to minimize the expected cost rate to the user. Finally numerical examples are given to illustrate the optimal maintenance polices.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.777-783
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• 2007

Life cycle costing is one of the most effective cost approaches when we choose a solution from series of alternative so the least long-term cost ownership is achieved. Life cycle costing in railway industry has been focused on the prediction of investment for railway vehicles. But in today, the life cycle cost, LCC, prediction on the aspect of operation and maintenance cost through whole life cycle is highly necessary. In this paper, we present a strategy for the development of life cycle cost estimation software on the aspect of maintenance strategies of railway vehicle. For this purpose, we suggested a structure of LCC software based on the UNIFE LCC model. And we developed a pilot version of software to evaluate the LCC model that we suggested for railway vehicle. We performed LCC analysis on the brake module of metro vehicle in case study and concluded that the software and model developed in this research could enough to support engineers in choosing better cost effective solutions from many alternatives.

• 산업경영시스템학회지
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• 제19권39호
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• pp.89-98
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• 1996

This paper is concerned with cost analysis model in free -replacement policy under the periodic maintenance policy The free-replacement policy with minimal repairable item is considered as follows; in a manufacturer's view point operating unit is periodically replaced, if a failure occurs between minimal repair and periodic maintenance time, unit is remained in a failure condition. Also unit undergoes minimal repair at failures in minimal-repair interval. Then total expected cost per unit time is calculated according to maintenance period Tin a viewpoint of consumer's. The expected costs are included repair cost and usage cost: operating, fixed, minimal repair and loss cost. Numerical example is shown in which failure time of item has beta distribution.

• Journal of the Korean Data and Information Science Society
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• 제22권4호
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• pp.775-784
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• 2011

본 논문에서는 비재생무료교체-수리보증이 종료된 이후의 수리가 가능한 시스템에 대한 주기적인 예방보전모형을 고려한다. 이러한 예방보전모형에 대하여 기대순환길이, 총기대비용 그리고 단위시간당 기대비용을 각각 유도하고자 한다. 또한 유도된 단위시간당 기대비용을 최소화하는 최적의 예방 보전주기와 예방보전횟수를 결정하는 방법에 대하여 자세히 설명한다. 끝으로 고장시간이 와이블분포를 따르는 경우에 최적의 주기적 예방보전정책을 결정하여 본다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2007년도 춘계학술대회 논문집
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• pp.328-333
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• 2007

Traditional maintenance planning is based on a constant maintenance interval for equipment life. In order to consider economic aspect for tm based preventive maintenance, preventive maintenance is desirable to be scheduled by RCM(Reliability-Centered Maintenance) evaluation. The main objective of RCM is to reduce the maintenance cost, by focusing on the most important functions of the system and avoiding or removing maintenance actions that are not strictly necessary. So, Markov state model is utilized considering stochastic state in RCM In this paper, a Markov state model much can be used for scheduling and optimization of maintenance is presented. The deterioration process of system condition is modeled by the stepwise Markov model in detail. Also, because the system is not continuously monitored, the inspection is considered. In case study, simulation results about RCM will be shown using the real historical data of combustion turbine generating unit in Korean power systems.

• Communications for Statistical Applications and Methods
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• 제6권1호
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• pp.99-106
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• 1999

This paper considers an imperfect repair model for which the repairable system is maintained preventively at periodic times and is replaced by a new system when a predetermined number of preventive maintenance has been applied. our main objective of this is to determine the optimal number of preventive maintenances before the system is replaced and the optimal length of interval between two consecutive preventive maintenances under a new repair model which is referred to as an ineffective preventive maintenance. Such a model assumes a periodic preventive maintenance in which the system is effectively maintained with a certain probability. Otherwise the system is not improved at all after each maintenance and thus the failure rate remains the same as before. The criteria to determine the optimal number of preventive maintenances and length of period is the expected cost rate per unit time for an infinite time span. We give the explicit expressions for the expected cost rate per unit time. Some numerical examples are presented for illustrative purposes.

• 융합정보논문지
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• 제11권3호
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• pp.125-131
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• 2021

모든 장비는 지속적인 사용에 의해 공정의 생산성과 경제성은 감소한다. 그러므로 일정 시점에서는 공정평균이동 문제라는 설비에 대한 예방보전이 필요하다. 설비의 보전시기를 결정함에 있어, 우리는 기존 연구에서 부분적으로 진행되어 온 보전모형들을 확장하고 통합함으로써 다양한 상황이 발생하는 생산 현장을 반영한 보전모형을 제시하고자 한다. 이를 구현하기 위해 제품규격은 상하한의 양쪽을 설정했으며, 적합품에 대해 품질손실함수를 도입했다. 마모수준에 대한 공정분산은 상수가 아닌 함수로 설정했으며, 특히 제품생산량과 보전비용에 있어서는 마모수준에 대한 함수를 개발하여 적용했다. 이로써 본 연구는 현장의 다양한 공정에 대부분 적용할 수 있는 보전모형이 될 것으로 생각한다. 추후 연구에서는 보전모형을 구성하는 부적합비용, 품질손실비용, 보전비용에 더하여 제품판매로 인한 수익 항목을 추가한 전체 수익 최대화 문제로 전개할 수 있을 것이며, 크게는 본 연구의 모형에 고장률을 도입한 보전모형으로의 확장도 생각해 볼 수 있을 것이다.